Electrical outlets including AFCI, GFCI, power strips, and extension cords are used to connect portable appliances and other electrical equipment. Most of the commonly available outlets are not protected from improper connections and entry of foreign metallic objects causing a major concern for the safety of users especially children or inexperienced individuals. To control said improper connections, a mechanism, device or assembly so configured to resist the entry of any object other than a plug that matches the configuration and geometry of the outlet could be incorporated into the outlet housing cover. In North America, outlets are configured according to their voltage and current ratings and referred to as the National Electrical Manufacturers Association configurations or commonly known as NEMA configurations. The most common household electrical outlet configurations are the NEMA 1-15R, 2-15R, 2-20R, 5-15R 50, 5-20R 51, 6-15R 52 and 6-20R 53, respectively for 125V/15A ungrounded, 250V/15A ungrounded, 250V/20A ungrounded, 125V/15A with ground, 125V/20A with ground, 250V/15A with ground and 250V/20A with ground. Electrical plugs NEMA 1-15P 43, 2-15P 44, 2-20P 45 may be used with outlets of the same configuration with or without ground. For purposes of this patent application, the term “ungrounded” refers to a plug or a receptacle outlet without ground connection, whereas the term “grounded” refers to a plug or receptacle outlet with ground connection.
There are electrical outlets provided with tamper-resistant shutters commercially available, however, most of them are limited to two configurations including the most common NEMA 1-15R and 5-15R 50. Most prior art designs do not provide total tampering protection for outlets with ground. The NEMA 1-15R is similar to the NEMA 5-15R 50 except that it has no ground connection.
With the limited protection and features offered by prior art designs, there is always a possibility to develop a better and more effective tamper-resistant shutter device for electrical outlets as with the present invention.
The present invention would apply to at least 7 different electrical outlet configurations including NEMA 1-15R, 2-15R, 2-20R, 5-15R 50, 5-20R 51, 6-15R 52 and 6-20R 53. For purposes of this patent application, specific NEMA outlet configurations are used, however, the same principles, methods and techniques may be used for other configurations including those used in other countries and standards.
The present invention affords protection for multiple outlet configurations and saves production costs and tooling. The present invention ensures an effective tamper-resistant protection by allowing only plugs of matching configuration to be used with the outlet, avoiding electrocution or other harmful incidents. For someone to use anything but the proper plug, it would require knowledge of the operating mechanisms of the present invention to articulate the geometry of a matching plug. The present invention employs multiple levels of protection through interlocked mechanisms so the device would only operate when both plug blades are inserted simultaneously. In case of a grounded plug, the present invention includes a ground pin lockout release mechanism 34 so the shutters to the electrical outlet only open when a matching plug configuration is used.
U.S. Pat. No. 7,452,221B1 (November/2008 Oddsen et al) disclosed a shutter device for a NEMA 5-15R electrical outlet different from the present invention which is designed to accommodate multiple configurations with and without ground. The Oddsen et al patent also refers to a shutter device relying on a sliding and pivotal movement of shutter members through a side frame to position the openings in the shutter plate with the outlet contacts. This is different from the present invention which uses wedge-driven positioning members to release locking mechanisms.
U.S. Pat. No. 7,312,394B1 (December/2007 Weeks et al) disclosed a shutter device for a limited configuration different from the present invention which accommodates multiple configurations, with and without ground. The Weeks et al patent also refers to a shutter device with a stationary positioning member and the other moving in the same plane but in opposite direction. This is different from the present invention which uses wedge-driven positioning members to release locking mechanisms for the plug to be used with the outlet. The ground pin release mechanism disclosed in the Weeks et al patent is offset from the center of the assembly due to space limitations, whereas the present invention employs a ground-pin lockout release mechanism directly at the centerline of the shutter frame. This is made possible by the space-saving configuration disclosed in the present invention.
U.S. Pat. No. 7,868,719B2 (January/2011 Bazayev et al) disclosed a shutter device for a limited outlet configuration different from the present invention which is designed to accommodate multiple configurations, with and without ground. The Bazayev et al patent also refers to a shutter device with two similar sliding plates moving in unison to align the plug blades with the receptacle outlet contact points which is different from the present invention which uses wedge-driven positioning members to release locking mechanisms to open access holes for the plug to be used with the outlet. The Bazayev et al patent also did not disclose any provision for ground-pin lockout release mechanism, which is provided with the present invention.
US2010/0041259 A1 (February/2010 Ni) disclosed a shutter device for NEMA 5-15R and 5-20R electrical outlets different from the present invention which is designed to accommodate multiple configurations, with and without ground. The Ni patent refers to a shutter device with independently movable spring-activated elements which differ from the present invention using wedge-driven positioning members to release locking mechanisms for the plug to be used with the outlet. The Ni patent did not disclose any provision for ground-pin lockout release mechanism, which is provided with the present invention.
US2009/0236115 A1 (September/2009 Li) disclosed a shutter device for a NEMA 5-15R electrical outlet different from the present invention which is designed to accommodate multiple configurations, with and without ground. The Li patent refers to a shutter device with two opposing spring-activated members overlaid against each other through their side openings to resist tampering. The present invention is framed and wedge-driven positioning members are used to release locking mechanisms to access the outlet. The Li patent did not disclose any provision for ground-pin lockout release mechanism which is provided with the present invention.